The invention relates to a flow sensor element, which has at least one temperature-measuring element with at least one platinum thin film resistor and at least one heating element with at least one platinum thin film resistor. The at least one temperature-measuring element and the at least one heating element are arranged on a carrier element, formed from a ceramic foil laminate or a multi-part ceramic component. The carrier element has electric conductor paths and junction surfaces, for electrically contacting the at least one temperature-measuring element and also the at least one heating element. The further invention relates to the use of such a flow sensor element.
Such flow sensor elements are known from European published patent application EP 1 065 476 A1. There, a thermal air through-flow sensor is disclosed, in which a sensor element with a heating resistor and a resistance temperature-measuring element is arranged sunken in a recess of a ceramic laminate member and fastened with ceramic cement. Because of the adhesive bonding and the sunken arrangement of the sensor element with or in the ceramic laminate, the sensor element has a significant reaction inertia when the temperature of the measurement medium changes. The electrical contacts are covered in the flow region with an epoxy resin, so that use of the device at temperatures above 300° C. is not possible. In addition, the arrangement is expensive and hence cost-intensive.
Applicant's German patent application DE 102 25 602.0-33 (not yet published) discloses a temperature sensor with a total thickness of 10 to 100 μm and having a metallic foil substrate with an electrically insulating coating, on which a platinum thin film resistor is arranged as a temperature sensitive element. The temperature sensor is used in the region of a heat sink for a semiconductor element.
German published patent application DE 195 06 231 A1 discloses a hot film anemometer with a temperature measuring resistor and a heating resistor. The heating resistor is arranged like a bridge in a recess of a plastic support plate. The platinum temperature thin layer elements for the temperature-measuring resistor and for the heating resistor are arranged on a ceramic substrate, which is preferably made of aluminum oxide.
German published patent application DE 199 41 420 A1 discloses a sensor element for temperature measurement on a metallic substrate, which has an insulating layer as a membrane. The membrane spans over a recess in the metallic substrate. The platinum thin film is then arranged on the membrane in the region of the recess.
German published patent application DE 101 24 964 A1 discloses a sensor for measuring flow speed of gases or liquids with a support membrane constituted in the form of a flag. The support membrane is preferably made of a plastic and has an electrical conductive path of platinum and electrical supply leads. The use of such a sensor with a plastic support membrane is not possible at temperatures above 300° C.